So you do
distribute
a(b+c)=ab+ac
9(x+5)=9x+9 times 5=9x+45
7(x-3)=7x+7 times -3=7x-21
so now we have
9x+45+7x-21
group like terms
9x+7x+45-21
add
16x+24
simplified is 16x+24
Answer:
Adding 12 to the circle area is equal to the square area.
Or
s2 = 12 + A
Where
s = side of square
A = area of circle
So
s2 = 12 + 36
s2 = 48
Solve this for s to get the side length
7*10^8 is estimated as the product